Document processing systems commonly utilize technologies such as optical scanning and magnetic ink character recognition (MICR) to automatically read and process bank checks and other documents. As a document is processed through a system utilizing MICR, presentation of the document to a magnetic read head must be tightly controlled in order to prevent read errors. One factor affecting the rate of read errors is the speed of the document as it translates in front of the magnetic read head. Document processing systems commonly have sensing devices for measuring the speed of the moving document. The speed measurements are fed back to the processing system, which uses the data to perform processing functions, for example, to control positioning of the document at the read head.
Speed sensing devices typically are located away from the read head to avoid interference with the moving document or document drive apparatus. The processing system adjusts speed measurements to account for the distance between the speed sensor and the read head. However, as the document is moved along the processing path, it is subjected to a variety of forces that can render such adjustments inaccurate. For example, when the document is placed vertically on edge for processing, it can curl and buckle. Another source of inaccuracy can be a drive roller or drive wheel that pushes against the document surface at a location distant from the read head.
MICR read error rates also are affected by the extent to which the document contacts the read head while being read. Devices commonly are used to apply pressure to the moving document to urge it against the read head. The effectiveness of such pressure diminishes, however, with increasing distance from the read head.
Accordingly, there remains a need in the art for accurate measurements of the speed of a document as it is being read, so that speed feedback to the system can be used more effectively in document processing. It also would be desirable to apply pressure to the moving document as close to the read head as possible, and, in certain applications, to drive the document across the read head from a location as close to the read head as possible.